Beginning March 1, the airline will require customers seeking to travel with a pet to provide additional documents that show the passenger’s need for a support animal as well as proof of the animal’s training and vaccinations 48 hours prior to the flight.

The number of animals onboard flights has increased 150% since 2015 according to Delta. The airline now carries about 700 assistance animals each day.

The number of reported animal incidents on aircrafts has also increased — up 84% since 2016. This includes incidents of urination, defecation and biting. In 2017, one passenger was mauled by a 70-pound support dog on a flight in Atlanta.

“The rise in serious incidents involving animals in flight leads us to believe that the lack of regulation in both health and training screening for these animals is creating unsafe conditions across U.S. air travel,” John Laughter, Delta’s senior vice president for corporate safety, security and compliance, said.

Federal law allows service animals to fly in-cabin with their owners as long as they don’t pose a threat to the health and safety of other passengers.

However, Delta claims steep increase in the number of animals on flights over the last few years reflects an abuse of the policy.

“Customers have attempted to fly with comfort turkeys, gliding possums known as sugar gliders, snakes, spiders and more,” the airline said. “Ignoring the true intent of existing rules governing the transport of service and support animals can be a disservice to customers who have real and documented needs.”